This invention relates to an impact-absorbing vehicle canopy. More particularly, the invention pertains to a canopy. More particularly, the invention pertains to a canopy for a low-profile mining vehicle in which at least a portion of the canopy is displaceable in a fore-and-aft direction in order to minimize damage to the canopy in the event of impact with the mine walls.
Safety canopies are often provided on underground mining vehicles in order to protect the vehicle operator from falling debris. Such canopies are an absolute necessity on low-profile mining vehicles which are adapted for low overhead coal mines. Such mines may have a height of only 48 inches or so and often do not have adequately finished overhead surfaces.
The operating station in a low-profile mining vehicle has conventionally been positioned adjacent the side of the vehicle because, first, this enables the operator to easily position his vehicle with respect to one of the side walls of the mine, and second, such location simplifies the positioning of the drive train or other vehicle drive components on the opposite side of the vehicle. Canopies for the operating stations of low-profile vehicles have conventionally taken two basic forms. The first and simplest form merely consists of a four-sided cover supported by posts at each corner. This type of canopy is typically the strongest and easiest to produce, but it has several disadvantages. First, there must be a strong enough surface to support each of the four posts. Since, as noted above, the operating station is typically positioned adjacent the side of the vehicle, support means may not be present for the two outboard posts. This is particularly true when, as is often the case, the canopy is added by vehicle designers as almost an afterthought. A second disadvantage of this four post construction is that the two outboard posts obstruct the line of vision of the operator. A third and perhaps most important drawback with the four post type construction is that it often does not provide adequate protection to the operator since, on some vehicles, he is forced to lean in an outboard direction to determine the position of the vehicle. The operator would thus be in an exposed position when leaning outwardly in this fashion.
Due to the above reasons, the use of cantilevered canopies for low-profile mining vehicles has greatly increased over the last few years. Cantilevered canopies are typically supported by a pair of posts which are mounted inboard of the operating station and which extend, in a lateral direction, over the operating station, thereby protecting the operator. Thus, the posts which previously had been mounted to the lateral periphery of the vehicle are dispensed with, thereby eliminating the obstruction to the vision of the operator which was present in the four post configuration. Cantilevered canopies also sometime extend slightly beyond the lateral periphery of the vehicle in order to protect the operator in the event he feels the need to lean outwardly.
Despite the desire to protect the operator who is leaning outwardly beyond the lateral periphery of the vehicle, vehicle manufacturers have been reluctant to extend cantilevered canopies in this manner. The primary reason for this reluctance is because, with the canopy overhead and out of the line of vision of the operator, the operator may inadvertently direct his vehicle in such close proximity to the side wall of the mine that the lateral edge of the canopy contacts the mine wall. This is particularly possible when, as is often the case, the upper part of the mine wall is curved or arched toward the opposing wall. In fact, where such curvature exists, the canopy will often be the first part to contact the side wall even if the canopy does not extend beyond the periphery of the vehicle. When such contact does occur, the momentum of the moving vehicle will often result in substantial damage to the canopy even if only the outer edge contacts the side wall of the mine. Even more important than damage to the canopy is the fact that the canopy may be impacted downwardly toward the operator positioned therebelow. Faced with a rapidly collapsing canopy, the operator may not be able to instantly stop the vehicle. Thus, the danger of serious injury to the operator exists.
Prior art patents fail to provide a solution to the aforedescribed problems. The following U.S. patents all teach the use of canopies which are pivotable or otherwise displaceable, but such displacement is effected either manually by the operator or through a mechanism provided on the vehicle; none of these patents discloses means which automatically displace the canopy upon impact: U.S. Pat. Nos. 4,202,565; 4,173,371; 3,934,679; 3,917,310; 3,912,297; 3,829,121; 3,713,688; 3,584,897; 3,336,074; 3,259,211. Moreover, none of these patents discloses canopy means for low-profile vehicles. The following U.S. patents teach the desirability of a vertically reciprocable canopy for a low-profile vehicle, but fail to suggest any solution to the problems set forth above: U.S. Pat. Nos. 4,078,629; 4,065,167. Finally, U.S. Pat. No. 4,095,839 discloses a protective cover for a crane-type vehicle which is resiliently mounted, but similarly fails to provide any suggestion of a solution to the problem of developing an impact-absorbing canopy for a low-profile vehicle.
Hence, it is a primary object of the present invention to provide an improved vehicle canopy which effectively and reliably overcomes the aforementioned drawbacks and limitations of the prior art proposals. More specifically, the present invention has as its objects one or more of the following taken individually or in combination:
(1) The provision of a canopy for a low-profile mining vehicle which increases the safety to the vehicle operator without substantially increasing the cost of the vehicle;
(2) To provide a canopy for a low-profile mining vehicle which is less likely to collapse than prior art designs, but which does not obstruct the visibility of the operator;
(3) To provide an effective means of protecting the operator of a low-profile mining vehicle without substantially increasing the height of the vehicle;
(4) The development of a vehicle canopy which is simple in construction, yet which is strong enough to provide a high degree of safety to the operator of the vehicle; and
(5) The provision of an improved mining vehicle canopy which may be mounted to conventional mining vehicles.